Been using multi-account containers for a few years now. Don't know what I'd do without it now.
One feature I wish they would add is to be able to delete cookies, etc. by container leaving other containers alone.

Useful and needed in modern web browsing to separate your personal data out of big brothers.

Works great in general. If you are using containers combined with proxies or VPN, be advised that Service Workers ignore container settings. Hence, you might be generating traffice outside of the proxy/VPN you think you are using.

非常希望在手机版firefox有这个功能

Used to be one of my favourite extensions to firefox. But after an update they've started asking whether a particular page should open in a specific container, very often every single time i want to open a page. Just give me an option to never ask for that, ever. If i want something to launch in a particular container, Ill just do it manually.